(57) A method of manufacturing an article (10) from two metal workpieces (30,32), the
first and second metal workpieces (30,32) define the outer profile of the article
(10). The second workpiece (32) is thicker than the first workpiece (30). The first
workpiece (30) has two flat surfaces (34,36) and the second workpiece has one flat
surface (38) and one machined (42) surface (40). Stop of is applied to surface (34)
to prevent diffusion bonding at preselected areas. The workpieces (30,32) are assembled
into a stack (58) so that the flat surfaces (34,38) are in abutment. Heat and pressure
are applied to diffusion bond the workpieces (30,32) together to form an integral
structure (60). The integral structure (60) is placed in a die such that the first
workpiece (30) faces a convex surface of the die. The integral structure (60) is heated
to cause the integral structure (60) to be hot creep formed on the convex surface
of the die. The integral structure (62) is hot formed in a superplastic forming die
by heating and internally pressurising the integral structure (62) to cause a preselected
area of the second workpiece to be hot formed to produce the article (10).
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